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/*****************************************************************************
Copyright (c) 2006, 2011, Oracle and/or its affiliates. All Rights Reserved.
This program is free software; you can redistribute it and/or modify it under
the terms of the GNU General Public License as published by the Free Software
Foundation; version 2 of the License.
This program is distributed in the hope that it will be useful, but WITHOUT
ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.
You should have received a copy of the GNU General Public License along with
this program; if not, write to the Free Software Foundation, Inc.,
51 Franklin Street, Suite 500, Boston, MA 02110-1335 USA
*****************************************************************************/
#include "ut0wqueue.h"
/*******************************************************************//**
@file ut/ut0wqueue.cc
A work queue
Created 4/26/2006 Osku Salerma
************************************************************************/
/****************************************************************//**
Create a new work queue.
@return work queue */
UNIV_INTERN
ib_wqueue_t*
ib_wqueue_create(void)
/*===================*/
{
ib_wqueue_t* wq = static_cast<ib_wqueue_t*>(mem_alloc(sizeof(*wq)));
/* Function ib_wqueue_create() has not been used anywhere,
not necessary to instrument this mutex */
mutex_create(PFS_NOT_INSTRUMENTED, &wq->mutex, SYNC_WORK_QUEUE);
wq->items = ib_list_create();
wq->event = os_event_create(NULL);
return(wq);
}
/****************************************************************//**
Free a work queue. */
UNIV_INTERN
void
ib_wqueue_free(
/*===========*/
ib_wqueue_t* wq) /*!< in: work queue */
{
mutex_free(&wq->mutex);
ib_list_free(wq->items);
os_event_free(wq->event);
mem_free(wq);
}
/****************************************************************//**
Add a work item to the queue. */
UNIV_INTERN
void
ib_wqueue_add(
/*==========*/
ib_wqueue_t* wq, /*!< in: work queue */
void* item, /*!< in: work item */
mem_heap_t* heap) /*!< in: memory heap to use for allocating the
list node */
{
mutex_enter(&wq->mutex);
ib_list_add_last(wq->items, item, heap);
os_event_set(wq->event);
mutex_exit(&wq->mutex);
}
/****************************************************************//**
Wait for a work item to appear in the queue.
@return work item */
UNIV_INTERN
void*
ib_wqueue_wait(
/*===========*/
ib_wqueue_t* wq) /*!< in: work queue */
{
ib_list_node_t* node;
for (;;) {
os_event_wait(wq->event);
mutex_enter(&wq->mutex);
node = ib_list_get_first(wq->items);
if (node) {
ib_list_remove(wq->items, node);
if (!ib_list_get_first(wq->items)) {
/* We must reset the event when the list
gets emptied. */
os_event_reset(wq->event);
}
break;
}
mutex_exit(&wq->mutex);
}
mutex_exit(&wq->mutex);
return(node->data);
}
/********************************************************************
Wait for a work item to appear in the queue for specified time. */
void*
ib_wqueue_timedwait(
/*================*/
/* out: work item or NULL on timeout*/
ib_wqueue_t* wq, /* in: work queue */
ib_time_t wait_in_usecs) /* in: wait time in micro seconds */
{
ib_list_node_t* node = NULL;
for (;;) {
ulint error;
ib_int64_t sig_count;
mutex_enter(&wq->mutex);
node = ib_list_get_first(wq->items);
if (node) {
ib_list_remove(wq->items, node);
mutex_exit(&wq->mutex);
break;
}
sig_count = os_event_reset(wq->event);
mutex_exit(&wq->mutex);
error = os_event_wait_time_low(wq->event,
(ulint) wait_in_usecs,
sig_count);
if (error == OS_SYNC_TIME_EXCEEDED) {
break;
}
}
return(node ? node->data : NULL);
}
/********************************************************************
Check if queue is empty. */
ibool
ib_wqueue_is_empty(
/*===============*/
/* out: TRUE if queue empty
else FALSE */
const ib_wqueue_t* wq) /* in: work queue */
{
return(ib_list_is_empty(wq->items));
}
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